The present invention relates to electric motors and more particularly to brushes and brush assemblies implemented therein.
Electric motors are used in a variety of applications, including power tools. Such electric motors generally include a motor shaft, a motor armature, a field pole, field windings, a commutator assembly, brush holders and electrical leads. The electrical leads selectively link brushes to a power source. The motor armature is fixed for rotation with the motor shaft and a series of copper conducting wires are wound in various patterns about peripheral slits. Ends of the wires are fused to the commutator. The commutator is fixed for rotation with the motor shaft and provides an electrical connection between the rotating armature and the stationary brushes. The brush holders each slidably support a carbon brush that is in sliding contact with the commutator. Generally, the stationary brushes are held in contact with an outside surface of the commutator by spring tension and complete the electrical circuit between the rotating commutator and a power source.
Various spring biased mounting configurations have been developed to maintain brush contact with the commutator. Effectiveness and wear durability of the brush is decreased when the brush is subjected to arcing. Arcing generally occurs as a result of the brush bouncing away from the commutator as rough spots and irregularities of the commutator pass under the brush. Prior art brushes include recesses formed therein for retaining an end of a biasing spring for effectively biasing the brush in contact with the commutator. These prior art recesses, however, tend to be overly complex and thus more difficult to manufacture. Further, prior art recesses fail to prohibit lateral movement of the biasing spring.
Therefore, it is desirable in the industry to provide an improved brush having a simplified recess. The recess should concurrently provide sufficient biasing of the brush in contact with the commutator to avoid arcing and other detrimental occurrences.
A brush assembly is provided for implementation in an electric motor. The brush assembly includes a base with a member to secure the base to a motor. A brush housing is associated with the base and has first and second open ends. A brush, defining an axis, is slidably supported within the housing between said first and second open ends. The brush extends from one of the first and second open ends. The brush includes a surface having a spring retention plunge. The spring retention plunge has an arcuate face angled relative to the axis. The brush assembly further includes a biasing member exerting a force directly on the arcuate face to bias the brush within the housing to contact with a commutator. An electrical connector is electrically coupled with the brush to electrically connect between the commutator and a power supply.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.